In For the Long Haul: 10 Years Since STS-115 (Part 1)

By Ben Evans, on September 3rd, 2016

Joe Tanner had already performed five EVAs before STS-115 left Earth. By the time he returned from the mission, he had completed seven EVAs and spent 46.5 hours outside a spacecraft. Even today, he stands as the 13th most seasoned spacewalker of all time. Photo Credit: NASA, via Joachim Becker/SpaceFacts.de

At first glance, shuttle mission STS-115—launched 10 years ago, this month—seemed to have it all: a rendezvous and docking with the International Space Station (ISS), multiple spacewalks by crew members of different gender and nationality, and an intense plate of robotics activity. Moreover, Commander Brent Jett, Pilot Chris Ferguson, and Mission Specialists Joe Tanner, Dan Burbank, Heidemarie Stefanyshyn-Piper, and Canada’s Steve MacLean officially restarted the on-orbit construction of the multi-national outpost in the wake of the Columbia tragedy. In the weeks preceding their 9 September 2006 liftoff, Jett noted that the four flight-seasoned veterans on his crew had always launched on-time, with no delays, which proved something of an omen. As circumstances transpired, STS-115 was delayed several times. In fact, after working together on the mission for more than 4.5 years, Jett’s team had the longest training template of any shuttle crew.

Formally announced by NASA in February 2002—having been assigned on 7 February, Stefanyshyn-Piper’s 39th birthday—the six astronauts were tasked with installing the P-3/P-4 segment onto the space station’s Integrated Truss Structure (ITS). This particular segment, as its name implied, formed part of the “port” side of the ITS and would be directly mated onto the P-1 segment, launched on STS-113 in November 2002. Weighing in excess of 35,000 pounds (15,875 kg) on the ground, the P-3/P-4 segment would provide a quarter of the station’s power capability. Its hexagonal-shaped P-3 component was connected to the Solar Alpha Rotary Joint (SARJ), which rotated the electricity-generating solar arrays, allowing them to continuously track the Sun. Finally, its P-4 component held the canisters for the array blankets themselves, which would be deployed in opposite directions to a total length of almost 240 feet (73 meters). On the ground, the integrated P-3/P-4 hardware measured about 45 feet (13 meters) in length, allowing it to fit snugly into the shuttle’s payload bay, but on-orbit it would dramatically expand to change the appearance of the entire ISS.

The configuration of the International Space Station (ISS) in the late summer of 2006, with the P-3/P-4 truss segment and deployed solar array wings clearly visible at right. Image Credit: NASA

Once installed, the arrays on the end of P-4 would each generate a couple of kilowatts of electrical power; effectively doubling the station’s power supply and roughly equivalent of meeting the needs of 30 average homes on Earth. With three spacewalks scheduled to performed by Tanner, Burbank, Stefanyshyn-Piper, and MacLean, STS-115 would contribute to making 2003 the most EVA-intensive year in history. All told, no fewer than 24 spacewalks were planned, spread across five shuttle missions and two long-duration ISS expeditions. With their launch originally targeted for April 2003, Jett’s crew would fly during a year which would see all but one element of the massive, 11-piece ITS completed, with dual pairs of solar arrays at its port and starboard extremities. Indeed, by the end of 2003, the ITS would have expanded in length from 134 feet (40.8 meters) to 310 feet (94.5 meters).

By the time that Columbia and her crew were lost during re-entry on 1 February 2003, the launch date for Jett’s mission had slipped to no earlier than 23 May. All shuttle flights were immediately stood down, pending the completion of the Columbia Accident Investigation Board (CAIB) and NASA’s efforts to return the fleet of three surviving orbiters—Discovery, Atlantis, and Endeavour—to operational flight status. During the course of the next few years, most of the original crews were partially reassigned, with two highly-experienced shuttle commanders rotated into management roles and others shifted onto other flights. However, unusually, the crew of STS-115 remained entirely intact, to such an extent that by the time they finally rose to orbit on 9 September 2006 an astonishing 1,656 days had elapsed since their assignment. This was far longer than any other single shuttle crew, including Commander John Young and Pilot Bob Crippen on STS-1, whose formal training spanned a little more than three years.

“You can’t stay focused for four years; it’s impossible,” said Brent Jett before the flight. In his mind, the most important role of the Commander was to provide leadership and prepare his crew for launch. “We’re one of the few crews that were assigned at the time of the accident. In fact, we were fairly close to launch; we’ve all stayed together. We haven’t had any crew changes. Our mission has stayed pretty much the same over the four years. So you don’t try to keep everybody focused: you let everybody, at the appropriate times, take a step back, get away from the mission a little bit, and then bring everybody back and have them peak at the right time.”

From her perspective, Stefanyshyn-Piper agreed. “When the Columbia accident happened, we were about three months from flight,” she remembered. “Up to that point, we had been marching along for a May 2003 launch date. After the accident, that obviously was put on hold.” During the down time, many members of the crew were detailed to support the actions of the CAIB and NASA’s efforts to return the shuttle flight to operations. The STS-115 crew periodically came back together for proficiency training and, for about a year Stefanyshyn-Piper undertook technical duties associated with cooling the U.S. space suits aboard the station. “That was something that helped me understand more about the suits, so now I know more about the suit and I know more about station systems,” she said. “We knew that we had a mission and that one day we would be going back to flying. Doing technical jobs and training together kept that focus that we needed.”

Following the resumption of shuttle operations after the loss of Columbia, STS-115 found itself in third place, bringing up the rear after a pair of logistics flights, STS-114 in July 2005 and STS-121 in July 2006. Originally targeted to launch in late August 2006, Jett’s mission met with delay when managers decided to replace securing bolts on Atlantis’ Ku-band communications antenna. Far more significant was the threat posed by lightning. On the 25th, a direct strike—the most powerful ever recorded at the Kennedy Space Center (KSC) in Florida—occurred on the lightning mast at Pad 39B. Additional delays were imposed to assess the potential damage and hopes to get Atlantis into orbit before month’s end came to nothing as Hurricane Ernesto regained power and prompted a rollback of the shuttle to the Vehicle Assembly Building (VAB). This produced an interesting situation. Late on the morning of the 29th, the STS-115 rollback commenced, but was halted on the crawlerway by early afternoon, when a decision was made to return to the pad. Meteorologists had determined that Ernesto would probably miss the Cape and its peak winds were anticipated to be somewhat lower than the maximum limit for retaining the vehicle on the pad.

An initial launch attempt on 8 September was called off, when one of four Engine Cutoff (ECO) sensors aboard the External Tank (ET) reportedly failed. The tank was drained and the other three sensors correctly indicated it as being “dry,” leading to a decision to allow a launch attempt on the 9th with three-quarters of the sensors operational. Without further ado, Atlantis roared into orbit at 11:15 a.m. EDT, heading for the space station and its incumbent Expedition 13 crew of Commander Pavel Vinogradov and Flight Engineers Thomas Reiter of the European Space Agency (ESA) and Jeff Williams of NASA.

The shuttle’s ascent was flawless, with the exception that Mission Control asked Jett and Ferguson to reconfigure the Flash Evaporator System (FES), which exhibited a temporary ice buildup. The reconfiguration cleared the issue and the FES operated normally throughout the remainder of the climb to space. Ahead lay a day of minute inspections of Atlantis’ exterior surfaces, to verify that no damage had been incurred during ascent. And after that, on 11 September, lay the space station and the resumption of construction work left undone in more than three years since Columbia’s untimely loss.

The second part of this article will appear tomorrow.

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